django lookups that span relationships - how to

Question

Hi,

I have an Address Model which has a ForeignKey to a Contact Model:

class Address(models.Model):
    street = models.CharField(max_length=25)
    postal_code = models.CharField(max_length=25)
    city = models.CharField(max_length=50)
    country = models.CharField(max_length=50)
    contact = models.ForeignKey(Contact, related_name='address to contact')

class Contact(models.Model):
    salutation = models.CharField(max_length=1, choices=salutation_choices, verbose_name="salutation")
    title = models.ForeignKey(Title, blank=True, null=True)
    ...

Now I want to filter my Contact objects based on data from the address object. Therefore I want to create a filter that span a relationship, following this part of the docu:

lookup that span relationship

I tried it like this:

result_set = Contact.objects.filter(address__street__contains='mystreet')

I'm getting the following error message:

Cannot resolve keyword 'address' into field. Choices are: address to contact, birthdate..

Actually the error message tells me that there is a field address to contact, but the question is how can I reference it?

Answer 1

You've set the related_name on Contact to address to contact. This is the value that Django uses for the backwards relation from Contact to Address - since this isn't a valid attribute name, I'm surprised it works at all.

Remove this attribute and your lookup should work.